Leishmania tarentolae, Trypanosoma lewisi, and Crithidia sp.: a comparative study

On the basis of the unsaturated fatty acids which they synthesize, protists can be grouped in a meaningful way. Thus, the unsaturated fatty acids of the true slime mold are identical with the unsaturated fatty acids of the soil amoebae Acanthumoeba and Hartmannella but have no resemblance to those of the cellular slime mold Dictyostelium. Among the zooflagellates, Leishmania enriettii and Leishmania tarentolae synthesize unsaturated fatty acids that are very similar to those of the phytoflagellates Euglena, Ochromonas, and Chlamydomonas, while Trypanosoma lewisi and especially Crithidia have a different pattern of unsaturated fatty acids which more closely resembles that of the ciliated protazoa. The unsaturated fatty acids of the true slime mold Physarum polycephulum include oleate, linoleate, 11-eicosenoate, 11,14eicosadienoate, 8,11,14-eicosatrienoate, and arachidonate. L. tarentolae synthesizes 6,9,12-octadecatrienoate and 9,12,15octadecatrienoate as well as polyunsaturated 20and 22-carbon fatty acids derived from both of these 18-carbon acids. T . lewisi synthesizes 6,9,12-octadecatrienoate. Crithidia synthesizes 6,9,12octadecatrienoate, 8,11,14-eicosatrienoate, and 4,7,10,13,16docosapentaenoate but not 9,12,15-octadecatrienoate or any acids derived from it. Leishmania and Trypanosoma have been shown to convert stearate directly to oleate.